Various tubular structures within the human body may come to contain materials, whether of the body's origin or man-made, that are undesirable. For example, stones may develop in the biliary or excretory systems, blood clots may form in blood vessels, or surgically implanted devices, such as catheters, may have fragments break off. For most of these situations, surgical intervention has traditionally been the primary means of retrieval and treatment.
Recently, however, various interventional radiological techniques have been developed which allow removal of such undesirable material. Such techniques involve the introduction of guide wires and catheters, or other medical devices, into the lumen of the tubular structures through introducer sheaths.
In one type of interventional radiological technique, various baskets, such as the SEGURA basket, manufactured by the Meditech company of Watertown, Mass., are used for trapping stones in the biliary and excretory tracts. Unfortunately, such devices are not easily inserted into, or manipulated within, the lumen of a human body's tubular structures. The baskets also generally contain wire mesh that may damage the interior walls of tubular structures.
Interventional radiologic techniques have been developed in which pharmacologic agents, such as urokinase, are used through catheter directed infusion to dissolve blood clots. This dissolving of clots is a relatively lengthy process and is extremely expensive. Furthermore, the process poses significant risks to the patient, the most serious of these being the precipitation of bleeding elsewhere in the body.
In U.S. Pat. No. 4,927,426 to Dretler, there is disclosed a device for capturing and disintegrating kidney stones and the like. The device features a snare that passes through the lumen of a catheter. Once the catheter is positioned within a passage of the human body, such as the urinary tract, the snare may be extended out of the catheter's distal end in an axial direction so that it may capture a kidney stone. The catheter has an elastomeric structure on its distal end which is inverted on itself as the kidney stone is drawn axially into the lumen of the catheter. The snare features an elongated tube through which a laser fiber passes. This allows the kidney stone to be disintegrated as it is held within the catheter. A disadvantage of this device, however, is that it features a profile that would preclude introduction into the vascular system. Furthermore, the elastomeric structure on the distal end of the catheter has undesirable consequences, as will be discussed below.
U.S. Pat. No. 5,092,839 to Kipperman discloses a method and apparatus for removing thrombus and plaque from a coronary artery. The apparatus features a balloon catheter disposed through the lumen of a guide catheter. The guide catheter features an expandable distal tip. Once the device is positioned within the artery, the balloon is inflated to expand the distal tip of the guide catheter. The balloon is then deflated and the distal tip of the guide catheter retains its expanded shape. The balloon catheter is then extended out from the distal tip and beyond the occluded portion of the artery and is once again inflated. The inflated balloon is then retracted back into the guide catheter, carrying with it residual pieces of thrombus and/or plaque which had been dislodged from the artery wall. A disadvantage of this apparatus and method, however, is that, in order to properly expand the distal tip of the guide catheter, the balloon must be precisely positioned. Furthermore, once the distal tip is expanded, it cannot be contracted. This would make removal from the patient's body or advancement further into the artery difficult if not impossible.
In order to accommodate the retrieval and removal of foreign bodies that are larger than the inner diameter of their distal tips, a number of sheaths and catheters have been constructed from elastomeric substances. An example is the EVC catheter available from the Applied Medical corporation of Laguna Beach, Calif. A disadvantage of existing elastomeric sheaths and catheters, however, is that, because of their elastomeric construction, they are easily deformed in an accordion-like fashion when an object is brought up forcefully against their orifices. Furthermore, due to their deformability, such sheaths and catheters may be peeled back during introduction through the skin or while entering the target structure. This could render the device useless and may possibly result in damage to the skin or target structure.
Accordingly, it is an object of the present invention to provide a catheter, which may be in the form of a typical catheter, a guide catheter or an introducer sheath, and a method of use by which a variety of undesirable materials may be removed from tubular structures within the human body.
It is also an object of the present invention to provide a catheter with a lumen which may be easily expanded once the catheter is introduced into a tubular structure of the human body so as to allow for passage of materials into the tip of the catheter for easier removal from the body.
It is a further object of the present invention to provide a catheter with an expandable lumen that is elastic so that it may be contracted back to its original size while in a tubular structure in the human body.
It is a further object of the present invention to provide a catheter which allows for elastic expansion of its lumen while maintaining adequate longitudinal strength to resist accordion-like deformation.
It is still a further object of the present invention to provide a catheter which allows for elastic expansion of its lumen and may be easily introduced and withdrawn from a tubular structure of the human body.